The present application is a divisional application of U.S. patent application Ser. No. 09/660,581 filed Sep. 12, 2000, now U.S. Pat. No. 6,905,834 issued Jun. 14, 2005, said application being a continuation-in-part application of U.S. Ser. No. 08/978,439 filed Nov. 25, 1997, now U.S. Pat. No. 6,117,643 issued Sep. 12, 2000, the entire contents of which are specifically incorporated herein by reference in its entirety.
The United States government has rights in the present invention pursuant to grant number DE-FG05-94ER61870 from the Department of Energy and grant number F49620-89-C-0023 from the United States Air Force.